Much of the world may be going mobile, but the desktop PC is still going strong. The reason is simple: A desktop still gives you a lot more per dollar.

Features such as quad-core processors, 6- or 8GB of memory, discrete graphics and Blu-ray drives—all rarities in laptops other than pricey desktop replacements—can be easily found in desktops that cost $1,000 or less.

Like laptops, desktops come in all shapes and sizes. So-called small form-factor desktops take up less space in a home office, but they can also be used as home theater PCs in a living room. Nearly all major computer makers now offer clutter-free all-in-one PCs—including several models with touchscreens—but Apple’s iMac remains the one to beat in this growing category.

The Mini Tower, which no longer looks so mini, is still a great choice for a performance or gaming PC because it offers lots of features and makes it easy to expand the memory, upgrade a graphics card or add new drives.

Whichever type you chose, you’ll be surprised at just how far your desktop dollar will go this holiday season.

Apple iMac
The latest iMac looks exactly the same from the outside. It has the same iconic aluminum shell, a glossy LED backlit display and the same ports (with a minor update to the SD card slot to support higher-capacity cards).

But inside it’s a different story as Apple has upgraded the CPU, memory and graphics, resulting in on the fastest all-in-ones available. The 21.5-inch version starts at $1,199 with a 1920x1080 resolution display, 3.06GHz Intel Core i3 dual-core processor, 4GB of memory, Radeon HD 4670 graphics with 256MB, a 500GB hard drive, and a slot-loading SuperDrive.

The $1,499 configuration has faster graphics and a 1TB hard drive. Its big brother is still the only all-in-one with a 27-inch display featuring a resolution of 2,560x1,440 pixels; Windows-based all-in-ones top out at 24 inches. The 27-inch iMac starts at $1,699 with a 3.20GHz Intel Core i3, 4GB of memory, Radeon HD 5670 graphics with 512MB, a 1TB drive and slot-loading SuperDrive.

As with the 21.5-inch, that configuration delivers very good performance, but Apple also offers a $1,999 version with a quad-core processor (the 2.8GHz Core i5) and Radeon HD 5750 graphics with 1GB. All of the iMacs also come with an Apple Wireless Keyboard and Magic Mouse, Mac OS X 10.6.2 Snow Leopard and the recently-announced iLife 11 suite.

Other computer makers continue to evolve their all-in-one designs—with some good results—but they are still no match for the iMac.

Gateway SX series
Gateway’s SX series is equal parts small form-factor desktop, budget desktop, and with the latest version home-theater PC. Whatever you choose to do with it, the SX series is a great little desktop.

The SX is a mini-tower that is less than four inches and sits 10.5 inches tall. There are numerous configurations to choose from ranging from $500 to $600 with both Intel and AMD processors. CNET recently tested a $550 configuration, the SX2850-33, with a 3.2GHz Core i3-550 dual-core processor, 4GB of memory, 640GB hard drive, DVD SuperMulti drive and 802.11b/g/n wireless.

The integrated WiFi is a nice touch because it makes it easier to use the SX series in a living room without having to install an Ethernet jack or purchase a separate USB adapter. The other features depend on the configuration you choose, but Gateway offers configurations with 5.1-channel audio, HDMI, IEEE 1394 FireWire, eSATA, and of course USB 2.0 and VGA out.

Best of all, the Gateway SX series performs like a much bigger desktop.

HP Pavilion p6500 series
The basic design of HP’s mainstream Pavilion desktop remain unchanged, though some Magnesium Edition configurations now come with a metallic gray case.

The Pavilion p6500 series comes in either Intel- or AMD-based versions with a wide range of models and configurations. As a result, this mainstream system really spans several categories from budget configs with under-powered AMD Sempron and Intel Celeron processors starting around $300 all the way up to models with Intel Core i7 quad-core processors and discrete graphics that cost more than $1,000.

In between are some nice mainstream configurations. For example, the p6640f Magnesium Edition is currently $700 with an AMD Phenom II 925 quad-core processor, 8GB of memory, Radeon HD 4200 integrated graphics, a 1TB hard drive, SuperMulti DVD Burner with LightScribe and 802.11b/g/n wireless.

For the same price, you can pick up the p6680t with a 3.2GHz Intel Core i5-650 dual-core processor, 6GB of memory, Radeon HD 5450 discrete graphics with 512MB, 640GB hard drive, and SuperMulti DVD burner.

Of these two, I would recommend the Intel-based system with discrete graphics for most mainstream users, but either way you’ll be getting a very solid desktop for $700.

Gateway FX series
Gateway’s top-of-the-line FX series is making a repeat appearance on our annual Holiday Gift Guide thanks to its blend of awesome hardware at a nice price. In a crowded retail market, Gateway has chosen to offer lots of memory, discrete graphics and beefy power supplies as a way to stand out from the crowd.

There are several FX configuration to choose from, but the Gateway FX6803-35, one of the newer configurations, is a good example. This $1,500 configuration includes a 2.8GHz Intel Core i7-930 processor, 9GB of memory, Radeon HD 5850 discrete graphics with 1GB, a 1.5TB hard drive and a Blu-ray drive.

You can easily build more powerful gaming PC by working with a boutique vendor such as Falcon Northwest, Maingear or Velocity Micro, but these systems can easily cost hundreds or even thousands more. And let’s face it, if you are looking for a $4,000 gaming rig, you don’t need a Holiday Gift Guide to help out.

Back here in the real world, the Gateway X series pack plenty of power for even the most demanding games at very competitive prices.